Winter wheat in the Texas Rolling Plains is utilized both as forage and grain crop on more than 50% of the wheat sown, and employs conventional tillage in a semi-arid region prone to severe soil erosion by wind and water. The study compared forage and grain yield response to pre-plant and top-dress N application in no-till and conventional-till dual-use wheat production systems. Five pre-plant N levels, two tillage systems, and one top-dress N application were evaluated. There was a linear increase in forage production with increasing pre-plant N application, and no significance difference in forage yield between conventional- and no-till in 3 of 4 yr. Grain production increased with increased pre-plant N, while top-dressed N enhanced grain yield an additional 20 to 40%. In 2 of 4 yr, conventional-till resulted in increased grain yield over no-till by about 10 to 12 %. Top-dressed N resulted in significant yield increases in all pre-plant N treatments but with the greatest yield increases from the 0 and 34 kg ha -1 pre-plant N treatments. Soil analysis data indicate that following poor wheat production years, residual nitrate N can be substantial and could offset N fertilizer requirements for the following wheat crop.

Grain sorghum [Sorghum bicolor (L.) Moench] is frequently planted in late June and early July in many parts of the Rolling Plains. Late planting results in grain maturing under unfavorable environmental conditions, prolonging high grain moisture content. Field studies were conducted at the Chillicothe Research Station, Chillicothe, TX to evaluate grain sorghym desiccants that could accelerate grain moisture loss. Desiccation treatments of sodium chlorate at 6.7 and 13.4 kg/ha or paraquat at 0.7 and 1.4 kg/ha were applied to a medium-late-maturing grain sorghum hybrid. In both years, desiccation treatments did not affect grain moisture loss during the 16 days after treatment. These results indicate that desiccants are generally ineffective in reducing grain moisture for late-planted sorghum in the Rolling Plains of Texas especially when grain moisture is < 24% at application and high relative humidity follows desiccant application.

Cotton seedlings are easily damaged by wind and wind blown soil in the semiarid Southern Great Plains. Cover crops offer protection to seedling cotton. The 3-year study was conducted near Vernon, Texas to determine biomass persistence of chemically terminated wheat and rye cover crops following six application rates of glyphosate. Treatments were applied at the boot or at the 50% heading stage of growth. The amount of standing biomass at 0 to 1 ft, 1 to 2 ft, and > 2 ft was estimated 4 wks after application and expressed as a percentage of the total biomass or percent persistence. Percent control or kill was also recorded. A successful treatment was defined as >90% control and > 15% standing residue above 1 ft. Results indicate that rye and wheat provided acceptable stubble persistence when terminated with at least 0.38 lb ai/ac glyphosate at 50% heading. Higher application rates of glyphosate did not increase control (> 90% kill) of the cover crop, were less cost effective, and resulted in decreased stalk persistence. Observations on early plant development, increased biomass, stand establishment under adverse environments, and seedling survival under cold, wet conditions favor rye as the cover crop of choice in semiarid environments.

Dual-purpose wheat (Triticum aestivum L.) systems are an important practice in the Southern Great Plains of the United States. As no-till receives increasing interest, there are concerns that grazing no-till wheat increases soil compaction and reduces rainfall infiltration. The objective of this study was to evaluate runoff characteristics as impacted by tilling dual-purpose, no-till wheat systems using conventional and varying aeration methods. Tillage treatments included (1) no-till; (2) conventional till; and aeration roller angles of (3) 0°, (4) 5°, and (5) 10°. These treatments were evaluated on two grazing systems: (1) graze out and (2) graze/grain. Rainfall simulators were used to provide four storm events: two after tillage implementation and prior to grazing and two after harvest and grazing season. When runoff events occurred within three weeks of aeration, 5° and 10° roller angles reduced runoff volume, increased infiltration, and reduced nutrient losses compared to no-till. However, six weeks after tillage, no-till runoff volumes were lower than all other treatments except the 10° aeration treatment. Soluble reactive phosphorus (P), total P, and ammonium-nitrogen (NH4-N) loads were significantly reduced by 5° and 10° aeration treatments when runoff events occurred within three weeks of tillage and immediately after fertilizer application. After 10 months of tillage implementation, infiltration was 10% to 52% greater on no-till plots compared to tilled treatments. For summer runoff events, graze out systems increased runoff by as much as 1.5-fold and decreased infiltration by as much as 1.3-fold compared to the graze/grain system. Overall, aeration was most effective in reducing runoff volumes and nutrient losses within three weeks after implementation and provided more positive effects than disking. If aeration is implemented with nutrient applications, nutrient losses could be reduced by more than 4-fold compared to no-till. Aeration may also be beneficial in no-till wheat systems that undergo much more intensive grazing systems than observed in this study. Ultimately, economic considerations must be carefully weighed when considering tillage of no-till, dual-purpose wheat systems.

Identifying management practices that conserve and protect water resources are very important to a wide variety of stakeholders within semiarid environments. The objective of this study was to develop water management strategies for transitioning tillage systems in cotton (Gossypium hirsutum L.) production within the Texas Rolling Plains when in a subsurface drip irrigation (SDI) system. Five irrigation regimes (0, 33, 66, 100, and 133% evapotranspiration [ET] replacement) and four tillage systems (conventional till, reduced till, no-till, and no-till with a terminated cover crop) were evaluated. The study was conducted for 3 yr and treatments were replicated three times in a randomized complete block design. Lint yields were not affected by the main effects of tillage or the interaction of tillage and ET replacement. In contrast ET replacement was a significant factor for lint yields, irrigation water use efficiency, and net returns. Greatest lint yields and net returns were achieved at 100% ET replacement. Fitted models indicated that optimum lint yields and net returns were achieved at 104.5% ET and 102% ET, respectively. Irrigation at 83% ET was within the 95% confidence interval for lint yield. Net returns were significantly higher for no-till systems compared with conventional till. Thus, adoption of conservation tillage systems should not negatively affect lint yield or net returns in deficit irrigated SDI cotton systems within the Texas Rolling Plains, particularly during the transition from intensively tilled systems to conservation tilled systems.

Adoption of no-till cropping systems continues to increase worldwide due to enhanced soil and water conservation, reduced inputs and maintained crop production. Soil compaction, particularly in grazed systems, can become a concern within no-till cropping systems and occasional tillage may be a method to relieve these concerns. However, there is no data within the US Southern Great Plains examining the impact of tilling long-term no-till wheat cropping systems and the potential subsequent impacts on runoff characteristics. The objective of this study was to evaluate the impact of tilling long term no-till wheat systems on runoff water quantity and quality. The study was conducted within a field that had been in no-till wheat with occasional grazing for seven years. Seven tillage treatments were evaluated, including: no-till, conventional till, and soil aeration using roller angles of 0°, 2.5°, 5°, 7.5°, and 10°. Rainfall simulation studies providing a 7cmh−1 storm event were conducted approximately three months after tillage. Results showed that conversion from no-till to conventional tillage increased runoff volume by 38%. Total sediment losses were at least 2.8 times greater from conventional till plots than no-till and aerated treatments. Nutrient concentrations were similar among tillage treatments. However, total P and ammonium-N loads in runoff water were significantly higher from conventional till plots compared with other tillage treatments. Aeration did not provide a consistent trend and generally provided no significant improvement in runoff characteristics compared with no-till. Initial results indicate no advantage of tilling long term no-till wheat systems in regard to runoff quality and quantity three months after tilling.

Ground water resources for irrigated agriculture are becoming increasing limited in semiarid regions of the world. Subsurface drip irrigation (SDI) and a no-till conservation tillage system were evaluated over 3 years on cotton ( Gossypium hirsutum , L.) production and fiber quality in north Texas. Subsurface drip irrigation significantly increased cotton yields over that from furrow irrigation in 2 of 3 yr. When averaged over 3 yr, the cover crop treatments on 1 and 2 m drip line spacing and a 100% ET replacement yielded numerically more than the companion treatments without a cover crop. Across years, the SDI treatments significantly increased loan values by an average of $0.045 kg −1 over furrow-irrigated cotton. Within SDI, deficit irrigation did not appear to affect cotton yield in proportion to the amount of restricted irrigation. In 2003, a 50% reduction in ET replacement under conventional tillage reduced yield only 22%, indicating that a 100% ET replacement may not be necessary to produce economically acceptable yields. Results from this study provide preliminary evidence that cover crops may actually prove beneficial under SDI systems and could play a role in developing best management practices that incorporate conservation tillage practices.

Wheat ( Triticum aestivum L.) production in the southern Great Plains is a unique enterprise that provides both high‐quality forage and a grain crop within the same growing season. However, information on fertility management programs to maximize forage and beef production in a dual‐use wheat production system is lacking. A 3‐yr, field‐scale production study was initiated on a Tillman clay loam near Vernon, TX, in 1999 to (i) determine the influence of P fertilizer and P fertilizer placement on forage, beef, and grain production from dual‐use wheat, and (ii) compare economic costs and returns of dual‐use and grain‐only wheat production systems. Varying numbers of stocker cattle ( Bos spp.) were placed in each pasture based on forage availability. Beef‐to‐forage allowance among pastures was kept relatively constant by adjusting cattle numbers monthly. Applying 20 kg P ha −1 yr −1 increased soil test P in the upper 15 cm two‐ to threefold, forage production 18 to 54%, and animal gains ha −1 27 to 29% compared with no P. With respect to forage and subsequent beef production, surface‐applied P was generally equal to or better than injected P. Average return between the graze‐plus‐grain and graze‐out systems was significant ( P < 0.0001) but not among fertilizer treatments ( P = 0.26), although surface‐applied P resulted in numerically higher returns each year. There was no significant system × fertilizer treatment interaction. However, during the study period, the graze‐plus‐grain system was clearly superior to the graze‐out system in generating higher net returns ($94 vs. $29 ha −1 ).

Guar production in the United States is limited to a relatively small region in the semiarid southern Great Plains of Texas and Oklahoma. The lack of POST broadleaf herbicides is a potential limiting factor to increased production. A greenhouse study was initiated in 2001 at the Texas A&M Research Center near Vernon, TX to evaluate guar tolerance to 10 POST herbicides typically used in soybean or cotton. Guar seedlings were grown in pots, and herbicides with appropriate adjuvants were applied to 3-wk-old seedlings at the registered rate (1X) and twice (2X) the registered rate for soybean or cotton. The study was repeated twice, with six replications in each run. Twenry-eight d after treatment (DAT), visual injury and aboveground dry weight of viable biomass were recorded for each plant. Significant differences (P = 0.05) were noted among herbicides for visual injury and viable biomass. Little or no differences in visual injury and aboveground dry weight were observed between the control (no herbicide applied) and the 1 X rate of 4-(2,4-dichlorophenoxy)butanoic acid, bentazon, or imazethapyr 28 DAT. A 1 X application rate of acifluorfen, imazamox, thifensulfuron, or bromoxynil caused minor visual injury of 7 to 9% and a reduction in dry weight of 8 to 23%. Pyrithiobac and chlorimuron caused 38 and 47% visible injury and a 35 and 58% reduction in dry weight, respectively. Guar was most sensitive to lactofen, with the 1 X rate causing 100% visual injury and no recoverable aboveground biomass. This greenhouse study identified three POST herbicide candidates with potential to control broadleaf weeds in guar without noticeable plant injury, and offers data to support herbicide registrations for this minor crop.

Hail damage can result in substantial economic loss to annual spring and summer crops. Crop insurance guidelines to assess hail damage on major crops are readily available to adjusters. However, research and guidelines to assess hail damage on minor crops is lacking and may limit their expansion. A dryland field study with guar [Cyamopsis tetragonoloba (L.) Taub.] was designed to determine the effect of simulated hail damage at two growth stages and three levels of defoliation on plant regrowth and bean yield. Experiments were conducted on a Miles fine sandy loam (fine-loamy, mixed, superactive, thermic Typic Paleustalfs) near Vernon, TX, from 2001 through 2003. A commercial grass trimmer was used to simulate hail damage by flailing plants to targeted defoliations levels of 33, 66, and 90% at 6 and 12 wk after emergence (WAE). Both final plant height and yield were reduced to a greater extent when plants were damaged at 12 WAE (grain-fill period) than at 6 WAE (early flowering). Regression analysis from data combined over years showed that guar yields were reduced 50% with a 66% defoliation level at 6 WAE, but required only 42% defoliation to reduce yield levels 50% with late-season defoliation. This is the first report of using a grass trimmer to simulate hail damage by shredding plant material rather than manually removing plants and plant parts. Results from this study also provide a basis for producers and insurance adjusters to quantify and estimate economic losses in guar due to hail damage at two growth stages.

In the Texas Rolling Plains, cool-season perennial grasses may complement limited forage availability in March–May and October–December. In two experiments conducted at Vernon, TX, on a sandy loam soil (fine-loamy, mixed, thermic Udic Paleustalfs), we evaluated productivity and persistence of crested [ Agropyron cristatum (L.) Gaertn. × A. desertorum (Fisch. ex Link) J.A. Schultes], hybrid [ Elytrigia repens (L.) Nevski × Pseudoroegneria spicata (Pursh) L‘ve], intermediate [ Thinopyrum intermedium (Host) Barkworth & D.R. Dewey], pubescent [ T. intermedium ssp. barbulatum (Schur) Barkw. & D.R. Dewey], and tall wheatgrass [ T. ponticum (Podp.) Barkworth & D.R. Dewey] under combinations of 3- or 6-wk defoliation frequency at 7.5- or 15-cm. About 64% more herbage yield was harvested from all species at the 7.5- vs. 15-cm defoliation height in the first, but only from crested, hybrid, and pubescent wheatgrass in the second growing season. Frequent defoliation increased herbage by 22% in Experiment A or 37% in Experiment B only in the first growing season. Tiller survival increased with frequent defoliation in intermediate wheatgrass by 33% in Experiment A and up to 70% in Experiment B, but decreased by 52% in hybrid and by 33% in pubescent wheatgrass in Experiment A, and up to 50% in Experiment B. Lower nighttime soil temperatures increased tiller survival during summer in swards defoliated at the 7.5- vs. 15-cm height. Wheatgrass productivity increased under intensive or frequent defoliation in the first, but declined in several species in the subsequent growing season, making their potential to complement forage base limited.

Wheatgrasses selected for improved forage yield and nutritional quality may be a less expensive alternative to wheat pastures in the Texas Rolling Plains. In this experiment, productivity and nutritional quality of seven introduced wheatgrass species and varieties was tested under an intensive (close and frequent defoliation) and extensive (recommended clipping height and less frequent defoliation) management system. The intensive management system resulted in a greater and better quality yield during the year of establishment. Plant survival appeared enhanced under intensive management after summer drought most probably because of a lower minimum (night) soil temperature when compared to the extensive management system. Results will help select wheatgrasses adapted to environmental conditions of North Texas for increase economic sustainability of perennial grass pastures.

Crop ScienceVolume 40, Issue 6 p. 1834-1835 Registration of Germplasm Registration of TXR91-SR6EI Annual Ryegrass Germplasm L.R. Nelson, Corresponding Author L.R. Nelson [email protected] Texas A&M Univ. REC, P.O. Box 200, Overton, TX, 75684Corresponding author ([email protected]).Search for more papers by this authorJ.W. Sij, J.W. Sij Texas A&M Univ. REC, P.O. Box 1658, Vernon, TX, 76384Search for more papers by this authorM.D. Lazar, M.D. Lazar Texas A&M Univ. REC, 6500 Amarillo Blvd. West, Amarillo, TX, 79106–1796Search for more papers by this authorK.J. McVeigh, K.J. McVeigh Willamette Valley Plant Breeders, Inc., 36100 HW 228, Brownsville, OR, 97327Search for more papers by this author L.R. Nelson, Corresponding Author L.R. Nelson [email protected] Texas A&M Univ. REC, P.O. Box 200, Overton, TX, 75684Corresponding author ([email protected]).Search for more papers by this authorJ.W. Sij, J.W. Sij Texas A&M Univ. REC, P.O. Box 1658, Vernon, TX, 76384Search for more papers by this authorM.D. Lazar, M.D. Lazar Texas A&M Univ. REC, 6500 Amarillo Blvd. West, Amarillo, TX, 79106–1796Search for more papers by this authorK.J. McVeigh, K.J. McVeigh Willamette Valley Plant Breeders, Inc., 36100 HW 228, Brownsville, OR, 97327Search for more papers by this author First published: 01 November 2000 https://doi.org/10.1002/j.1435-0653.2000.tb21516.x Registration by CSSA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References and Notes 1Nelson, L.R., F.M. Rouquette, Jr., and G.W. Evers. 1992. Registration of ‘TAM 90’ annual ryegrass. Crop Sci. 32: 828. 2Polle, E., C.F. Konzak, and J.A. Kittrick. 1978. Visual detection of aluminum tolerance levels in wheat by hematoxylin staining of seedling roots. Crop Sci. 18: 823–827. Volume40, Issue6November 2000Pages 1834-1835 ReferencesRelatedInformation

Field studies were conducted from 1992 to 1994 to evaluate herbicides applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) for red rice andEchinochloaspp. control in soybean. Metolachlor PPI at 3.4 kg ai/ha controlled red rice late season 90 to 92%. Alachlor at 4.5 kg ai/ha and SAN 582H at 2.2 or 3.4 kg ai/ha, PPI or PRE, metolachlor plus imazaquin at 2.8 + 0.14 kg ai/ha PRE, and quizalofop-P POST at 0.07 kg ai/ha provided 83 to 95% red rice control in at least 2 of 3 yr. The addition of imazaquin to metolachlor or pendimethalin did not improve red rice control. Early-seasonEchinochloaspp. control with trifluralin, pendimethalin, and pendimethalin + imazaquin applied PPI; metolachlor, SAN 582H at 2.2 or 3.4 kg/ha, and metolachlor + imazaquin applied PPI or PRE; alachlor, AC 263,222 + imazaquin, and AC 263,222 + imazethapyr applied PRE; and sethoxydim and quizalofop-P applied POST was 90 to 100% in at least 2 of 3 yr. However,Echinochloaspp. control decreased for all treatments later in the season. Pendimethalin applied PPI at 2.2 kg ai/ha or in mixture with imazaquin at 1.7 + 0.14 kg ai/ha injured soybean 14 to 34% in 2 yr. Trifluralin PPI, SAN 582H at 2.2 or 3.4 kg/ha PPI or PRE, imazaquin PPI, metolachlor + imazaquin PPI or PRE, and AC 263,222 + imazethapyr injured soybean 12 to 41% in at least 1 of 3 yr.

Rates of carbon dioxide exchange were determined using an infrared gas analyzer in an open chamber system in a field. During 1971 a fan was used to draw air through the chamber; the measured CO2 flux was approximately 40 percent greater than the highest rate reported in the literature. In 1972 two chambers were used: one under slight suction and the other under a slight pressure (compared with atmospheric pressure). The CO2 flux from the soil surface inside the "pressure" chamber was nearly an order of magnitude lower than inside the "suction" chamber. Dispersion equations were used to separate mass flow and diffusion components of the total flux. Simplified analysis showed that mass flow could account for the large CO2 flux with slight negative pressures inside the chamber.

AbstractUtilizing infrared gas analysis techniques, the effect of a 1‐hour exposure to 1, 3, or 5 ppm SO2 on apparent photosynthesis in the primary leaf of Pinto bean (Phaseolus vulgaris L. cv. Pinto) was studied as a function of three leaf ages. Generally, photosynthesis was reduced about 15, 70, and 90% for the respective concentrations regardless of leaf age. The initial inhibition of photosynthesis was not due to stomatal closure. Inhibition kinetics observed at 1 and 3 ppm SO2 for Pinto bean (Phaseolus vulgaris L.) were compared with those of SO2‐tolerant corn (Zea mays L.). At 1 ppm SO2, the kinetics of inhibition of photosynthesis for the two species were similar; however, at 3 ppm SO2, apparent photosynthesis in corn was inhibited less than in Pinto bean and recovered to a higher level following removal of SO2.